How Is High Blood Pressure Diagnosed?
Blood pressure is measured with a blood pressure cuff (sphygmomanometer). This may be done using a stethoscope and a cuff and gauge or by an automatic machine. It is a routine part of the physical examination and one of the vital signs often recorded for a patient visit. Other vital signs include pulse rate, respiratory rate (breathing rate), temperature, and weight.
The American Heart Association and the American College of Cardiology recommend specific steps to measure blood pressure in a medical setting.
- The patient should relax in a chair for at least five minutes, with the back supported and feet on the floor
- The patient should not have had caffeine, tobacco products or participated in any exercise for at least 30 minutes before the blood pressure check
- The patient should not talk for the five minute rest period
- The blood pressure cuff should not be placed over clothing; instead it should be placed directly on the skin
- The arm being tested should be supported or be rested on a table or arm rest
- The cuff being used should be the appropriate size for the patient
- Blood pressure should be checked at least two times, separated by 1-2 minutes, and an average taken to estimate that person’s blood pressure
- For the first visit for a blood pressure check, the blood pressure reading should be measured in both arms and the higher of the two readings should be used to decide upon treatment
When discussing blood pressure issues, the healthcare professional may ask questions about past medical history, family history, and medication use, including prescriptions, over-the-counter medications, herbal remedies, and food additives. Other questions may include lifestyle habits, including activity levels, smoking, alcohol consumption, and illegal drug use.
Physical examination may include listening to the heart and lungs, feeling for pulse in the wrist and ankles, and feeling and listening to the abdomen looking for signs of an enlarged aorta. The examiner may also listen in the neck for carotid bruits (sounds made by a narrowed artery in the neck) and in the abdomen for bruits made by an abdominal aortic aneurysm.
Eye examination with an ophthalmoscope may be helpful by looking at the small blood vessels on the retina in the back of the eyeball.
Blood tests may be done to assess risk factors for heart disease and stroke as well as looking for complications of hypertension. These include complete blood count (CBC), electrolytes, BUN (blood urea nitrogen), and creatinine and GFR (glomerular filtration rate) to measure kidney function. A fasting lipid profile will measure cholesterol and triglyceride levels in the blood. If appropriate, blood tests may be considered to look for an underlying cause of high blood pressure (secondary hypertension)including abnormal thyroid or adrenal gland function.
Ultrasound of the kidneys, CT scan of the abdomen, or both may be done to assess damage or enlargement of the kidneys and adrenal glands.
Other studies may be considered depending upon the individual patient's needs
- Electrocardiogram (ECG) may help evaluate heart rate and rhythm. It is a screening test to help assess heart muscle thickness. If hypertension is long-standing, the heart muscle has to hypertrophy, or get larger, to push blood against the increased pressure within the arteries of the body.
- Echocardiogram is an ultrasound examination of the heart It is used to evaluate the anatomy and the function of the heart. A cardiologist is required to interpret this test and can evaluate the heart muscle and determine how thick it is, whether it moves appropriately, and how efficiently it can push blood out to the rest of the body. The echocardiogram can also assess heart valves, looking for narrowing (stenosis) and leaking (insufficiency or regurgitation). A chest X-ray may be used as a screening test to look for heart size, the shape of the aorta, and to assess the lungs.
- Doppler ultrasound is used to check blood flow through arteries at pulse points in your arms, legs, hands, and feet. This is an accurate way to detect peripheral vascular disease, which can be associated with high blood pressure.
- Abdominal ultrasound is able to evaluate organs in the abdomen as well as blood flow in major arteries including the aorta, the renal arteries to the kidneys, and the mesenteric arteries to the stomach and intestine.
Elevated blood pressures in the medical setting may not necessarily reflect the individuals real status. "White coat hypertension" describes a patient whose blood pressure is elevated because of the stress of the visit to the doctor or other healthcare professional, and the worry that their blood pressure might be elevated. Repeated blood pressure checks at the doctor's office or the use of a home blood pressure monitoring device may be used to confirm that you have high blood pressure.